Heterosexual Self-Presentation and Other Individual- and Community-Based Correlates of HIV testing among Latino Men Who Have Sex With Men.

From 2010 to 2014, HIV diagnoses among Latino men who have sex with other men (LMSM) have increased by 14%, while diagnoses declined by 11% among white, non-Latino MSM. This health disparity is in part due to exposure to other LMSM with undiagnosed HIV infections. To effectively engage LMSM who are unaware of their serostatus, profiles of men differing in theorized determinants of HIV testing must be considered.

Influence of the neural microenvironment on prostate cancer.

Background: Nerves are key factors in prostate cancer (PCa), but the functional role of innervation in prostate cancer is poorly understood. PCa induced neurogenesis and perineural invasion (PNI), are associated with aggressive disease.

Method: We denervated rodent prostates chemically and physically, before orthotopically implanting cancer cells.

Biologic effect of neurogenesis in pancreatic cancer.

Pancreatic cancer (PaCA) is a deadly disease with few systemic therapeutic options. The head of the pancreas is the most innervated part and most common location of cancer. However, little is known about the contribution of the nerve-cancer interaction to facilitate pancreatic progression.

Biological correlates of prostate cancer perineural invasion diameter.

Perineural invasion is a symbiotic relationship between cancer cells and nerves and is most frequently seen in "neurotropic" cancers such as prostate cancer. It results in increased perineural space cancer cell growth and decreased apoptosis and induces nerve growth. Tissue microarrays were constructed from 640 radical prostatectomy specimens with prostate cancer.

Biologic correlates and significance of axonogenesis in prostate cancer.

Cancer-related axonogenesis and neurogenesis are recently described biologic phenomena. Our previously published data showed that nerve density and the number of neurons in the parasympathetic ganglia are increased in prostate cancer (PCa) and associated with aggressive disease. Tissue microarrays were constructed from 640 radical prostatectomy specimens with PCa.

Semaphorin 4F as a critical regulator of neuroepithelial interactions and a biomarker of aggressive prostate cancer.

Background: Semaphorin 4F (S4F) has roles in embryologic axon guidance and is expressed in adults. S4F is involved in cancer-induced neurogenesis.

Methods: Prostate cells were transfected with S4F retrovirus.

Biotin synthase mechanism: mutagenesis of the YNHNLD conserved motif.

Biotin synthase, a member of the "radical SAM" family, catalyzes the final step of the biotin biosynthetic pathway, namely, the insertion of a sulfur atom into dethiobiotin (DTB). The active form of the enzyme contains two iron-sulfur clusters, a [4Fe-4S](2+) cluster liganded by Cys-53, Cys-57, and Cys-60 and the S-adenosylmethionine (AdoMet or SAM) cosubstrate and a [2Fe-2S](2+) cluster liganded by Cys-97, Cys-128, Cys-188, and Arg-260. Single-point mutation of each of these six conserved cysteines produced inactive variants.

Escherichia coli biotin synthase produces selenobiotin. Further evidence of the involvement of the [2Fe-2S]2+ cluster in the sulfur insertion step.

Biotin synthase, a member of the "radical SAM" family, catalyzes the final step of the biotin biosynthetic pathway, namely, the insertion of a sulfur atom into dethiobiotin. The as-isolated enzyme contains a [2Fe-2S](2+) cluster, but the active enzyme requires an additional [4Fe-4S](2+) cluster, which is formed in the presence of Fe(NH(4))(2)(SO(4))(2) and Na(2)S in the in vitro assay. The role of the [4Fe-4S](2+) cluster is to mediate the electron transfer to SAM, while the [2Fe-2S](2+) cluster is involved in the sulfur insertion step.

Biotin synthase mechanism: an overview.

Biotin synthase, a member of the 'radical SAM' (S-adenosylmethionine) family, converts DTB (dethiobiotin) into biotin. The active form of the Escherichia coli enzyme contains two (Fe-S) centres, a (4Fe-4S) and a (2Fe-2S). The (4Fe-4S)2+/+ mediates the electron transfer required for the reductive cleavage of SAM into methionine and a DOA* (deoxyadenosyl radical).

Further investigation on the turnover of Escherichia coli biotin synthase with dethiobiotin and 9-mercaptodethiobiotin as substrates.

Biotin synthase, a member of the "radical-SAM" family, produces biotin by inserting a sulfur atom between C-6 and C-9 of dethiobiotin. Each of the two saturated carbon atoms is activated through homolytic cleavage of a C-H bond by a deoxyadenosyl radical, issued from the monoelectronic reduction of S-adenosylmethionine (SAM or AdoMet). An important unexplained observation is that the enzyme produces only 1 mol of biotin per enzyme monomer.

Fate of the (2Fe-2S)(2+) cluster of Escherichia coli biotin synthase during reaction: a Mössbauer characterization.

Biotin synthase, the enzyme which catalyzes the last step of the biosynthesis of biotin, contains only (2Fe-2S)(2+) clusters when isolated under aerobic conditions. Previous results showed that reduction by dithionite or photoreduced deazaflavin converts the (2Fe-2S)(2+) to (4Fe-4S)(2+,+). However, until now, no detailed investigation concerning the fate of the (2Fe-2S)(2+) during reduction under assay conditions (NADPH, flavodoxin, flavodoxin reductase) has been realized.

Iron-sulfur clusters of biotin synthase in vivo: a Mössbauer study.

Biotin synthase, the enzyme that catalyzes the last step of the biosynthesis of biotin, contains only [2Fe-2S](2+) clusters when isolated under aerobic conditions. Previous results showed that reconstitution with an excess of FeCl(3) and Na(2)S under reducing and anaerobic conditions leads to either [4Fe-4S](2+), [4Fe-4S](+), or a mixture of [4Fe-4S](2+) and [2Fe-2S](2+) clusters. To determine whether any of these possibilities or other different cluster configuration could correspond to the physiological in vivo state, we have used (57)Fe Mössbauer spectroscopy to investigate the clusters of biotin synthase in whole cells.

Biosynthesis of biotin and lipoic acid.

The genetics and mechanistic enzymology of biotin biosynthesis have been the subject of much investigation in the last decade, owing to the interest for biotin production by fermentation, on the one hand, and for the design of inhibitors with potential herbicidal properties, on the other hand. Four enzymes are involved in the synthesis of biotin from its two precursors, alanine and pimeloyl-CoA. They are now well-characterized and the X-ray structures of the first three have been published.

Enzyme-mediated sulfide production for the reconstitution of [2Fe-2S] clusters into apo-biotin synthase of Escherichia coli. Sulfide transfer from cysteine to biotin.

We previously showed that biotin synthase in which the (Fe-S) cluster was labelled with 34S by reconstitution donates 34S to biotin [B. Tse Sum Bui, D. Florentin, F.

Mössbauer studies of Escherichia coli biotin synthase: evidence for reversible interconversion between [2Fe-2S](2+) and [4Fe-4S](2+) clusters.

The nature and properties of the iron-sulphur (Fe-S) cluster in as-prepared and reduced biotin synthase of Escherichia coli have been investigated by Mössbauer spectroscopy. Our data clearly demonstrate that in the as-prepared sample, the cluster is present as [2Fe-2S](2+) with isomer shift, delta = 0.29 mm/s and quadrupole splitting, DeltaE(Q) = 0.

Biotin synthase mechanism: on the origin of sulphur.

Biotin synthase catalyses the last step of the biosynthesis of biotin in microorganisms and plants. The active protein isolated from Bacillus sphaericus and Escherichia coli contains an iron-sulphur (FeS) cluster. The native enzymes were depleted of their iron and inorganic sulphide and the resulting apoenzymes were chemically reconstituted with FeCl3 and Na2[34S] to give labelled (Fe34S) enzymes.

Biotin synthase, a new member of the family of enzymes which uses S-adenosylmethionine as a source of deoxyadenosyl radical.

The fact that biotin synthase, from Escherichia coli and Bacillus sphaericus, requires S-adenosylmethionine and a reducing system led us to postulate that this synthase could belong to the family of enzymes which use S-adenosylmethionine as a source of deoxyadenosyl radical, namely pyruvate formate-lyase, lysine 2,3-aminomutase, and anaerobic ribonucleotide reductase. We describe here experiments with S-[2,8-(3)H] adenosylmethionine and S-adenosyl-[methyl-3H]methionine which allowed the identification and quantification of the expected cleavage products, deoxyadenosine, and methionine. They are formed in equimolar amounts, in a ratio close to 3 with respect to the biotin produced.

Synthesis and biochemical properties of Z- and E-4,5-dehydrodethiobiotin.

Radical species are postulated intermediates in the formation of the carbon-sulfur bonds of biotin. It was of interest to examine the behaviour of unsaturated analogues which should give rise to allylic radicals. The two isomers of 4,5-dehydrodethiobiotin have been synthesized and labelled with 14C on their carboxylic acid group.

Highly purified biotin synthase can transform dethiobiotin into biotin in the absence of any other protein, in the presence of photoreduced deazaflavin.

Biotin synthase from Bacillus sphaericus has been purified to homogeneity from a recombinant strain. The UV-visible spectrum of the pure protein reveals the presence of a [2Fe-2S] cluster. The enzyme is active in the conversion of dethiobiotin to biotin in vitro, in the presence of NADPH, AdoMet and additional unidentified components from the crude extract of B.

Stimulatory factors for enzymatic biotin synthesis from dethiobiotin in cell-free extracts of Escherichia coli.

The activity of biotin synthesis from dethiobiotin was found in cell-free extracts of an Escherichia coli bioB transformant. Among the sulfur compounds tested, only S-adenosyl-L-methionine (AdoMet) had a significant effect, while methionine and cysteine were inert. The activity was linearly stimulated by increasing protein concentration.

The effect of intravenous phenylephrine on airway calibre in asthma.

Tracheobronchial vasoconstriction and subsequent reduction of airway wall thickness due to the alpha 1-agonist methoxamine, might be responsible for prevention of exercise-induced asthma, and reduction of bronchial hyperresponsiveness to methacholine increase in exercise performance in patients with impaired left ventricular function. Since bronchial wall oedema plays an important role in asthma, we have now investigated the bronchial response to the intravenously administered alpha 1-agonist, phenylephrine, in asthma of various severity. Increasing noncumulative intravenous phenylephrine doses (100 to 600 micrograms) were injected in 18 asthmatic subjects (three groups: mild asthma, mild asthma with recent acute attack, severe obstructive asthma) and in 11 control subjects.

Enzymatic conversion of dethiobiotin to biotin in cell-free extracts of a Bacillus sphaericus bioB transformant.

The activity of biotin synthase, responsible for biotin synthesis from dethiobiotin, was demonstrated in a completely defined reaction mixture with cell-free extracts of a Bacillus sphaericus bioB transformant. Among the sulfur compounds tested, only S-adenosyl-L-methionine was active, while L-methionine and L-cysteine had no significant effect. Protein concentrations higher than 15 mg/ml in the reaction mixture were needed to detect biotin synthase activity.

On the mechanism of biotin synthase of Bacillus sphaericus.

A cell-free system of a bioB transformant of Bacillus sphaericus, effecting the last step of biotin biosynthesis, namely the introduction of sulfur into dethiobiotin has been recently described. S-adenosyl methionine (SAM) is absolutely necessary for activity. We show here, through experiments with [35S]SAM and [35S]Cys, that the sulfur donor is not SAM but probably cysteine (Cys) or a derivative.

Assessing the discomfort of the whole-body multi-axis vibration: laboratory and field experiments.

Laboratory and field experiments were conducted to determine the best procedure for predicting the discomfort caused by multi-axis vibration. In the laboratory experiment, 11 seated subjects compared single-axis vibration in one axis to single-axis vibration in another axis, and compared dual-axis vibration to single-axis vibration. In the field experiment, 22 lorry drivers rated the discomfort of 16 different rides.

Refractoriness after hyperventilation-induced asthma.

It is still debated as to whether the bronchospasm induced by hyperpnoea in asthmatic subjects is followed by a period of refractoriness to a subsequent challenge. We studied, therefore, the effect of repeated challenges with eucapnic hyperpnoea in asthmatic subjects and compared it to that in normal subjects. Ten normal and 34 asthmatic subjects were challenged twice with a steady isocapnic hyperventilation (25 l X min-1 X m-2 BSA for 6 min) of dry air at room temperature.